Hi Steven,

Someone else may be able to help more with this, but it looks like you first
need to create a WebProxy object and use the GlobalProxySelection Class

How To Use WebClient Class To Make HTTP Requests

http://support.microsoft.com/default.aspx?scid=kb;en-us;328820#XSLTH312912112212
0121120120

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlr
fsystemnetwebproxyclasstopic.asp

 private bool SetProxy(string ProxyName)
 {
  //Set the proxy
  proxyObject = new WebProxy(ProxyName, true); // the true is to bypass
local address
  // You can get the nondynamic proxy settings from Internet Explorer 5.5.
  // by using the line below. This is what we use by default if you don't
set anything.
  //WebProxy proxyObject = WebProxy.GetDefaultProxy();
  // set the Credentials to the user's system credentials
  // This will handle NTLM authentication.
  // We will error trap for basic and then reqeust the username a password
  proxyObject.Credentials = CredentialCache.DefaultCredentials;
  GlobalProxySelection.Select = proxyObject;
  return true;
 }